Also Known as Bucket Trailer, U-dump, Dumping Trailer

A dump trailer is a trailer used for transporting loose material (such as sand, gravel, or dirt) for construction. A typical dump trailer is equipped with a hydraulically operated open-box bed hinged at the rear, the front of which can be lifted up to allow the contents to be deposited on the ground behind the truck at the site of delivery.

Source: U-Dump